Operator responsive programmed learning apparatus

ABSTRACT

In a rear projection viewer for showing a programmed viewing web having encoded frames thereon, light beams are directed across the face of a display screen onto photodetectors located about its periphery. A student can indicate a response to a projected answer coded scene, such as a question, by presenting a finger or other object at the face of the display screen at a selected answer point, thereby interrupting a light beam or beams. The photodetectors are connected to correlating circuitry which compares the student&#39;&#39;s response with information coded on the scene&#39;&#39;s frame. The next scene presented is program selected in accordance with what response the student registered.

United States Patent Frank [54] OPERATOR RESPONSIVE PROGRAMMED LEARNINGAPPARATUS [72] inventor: Lee F. Frank, Rochester, NY.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Jan. 25, 1971 [2!] Appl. No.: 109,276

[52] 0.8. CI. ..35/9 A [51] Int. Cl. ..G09b 7/08 [58] Field of Search..35/9 R, 9 A, 9 B, 8 R, 8 A, 35/22 R [56] References Cited UNITEDSTATES PATENTS 3,596,376 8/1971 Avedissian ..35/22 R 3,137,948 6/1964Wyckoff .3519 A 3,382,588 5/1968 Serrell et al ..35/9 A Oct. 17, 19723,522,664 8/1970 Lambright et al ..35/8 R Primary Examiner-Wm. H. GriebAttorney-R. W. Hampton, P. R. Holmes and R. W. Weig [57] ABSTRACT In arear projection viewer for showing a programmed viewing web havingencoded frames thereon, light beams are directed across the face of adisplay screen onto photodetectors located about its periphery. Astudent can indicate a response to a projected answer coded scene, suchas a question, by presenting a finger or other object at the face of thedisplay screen at a selected answer point, thereby interrupting a lightbeam or beams. The photodetectors are connected to correlating circuitrywhich compares the student's response with information coded on thescenes frame. The next scene presented is program selected in accordancewith what response the student registered.

13 Claims, 8 Drawing Figures PATENTEMU 17 I972 3.698.100

saw 1 or 6 E FRANK VENTOR.

BY gar AGENT PATENTEDw 11 m2 SHEEI 2 BF 6 FIG. 2b

LEE F FRANK AGENT PATENTEnum 1 1 m2 3.688.100

SHEET 3 BF 6 IMAGE AREA cumrjlbibbmmm UUOE LpL Ummm FIG. 7

- LEE F FRANK INVENTOR.

AGENT SHEET 5 BF 6 LEE F FRANK INVENTOR.

AGENT 0 0 5 m Lm OCT 1 7 I972 SHEEI 6 OF 6 FRAME I50 I52 I56PHOTODETECTOR CODED PHOTODETECTORSIQ ENABLING 1 FRAME CIRCUIT READERRESPONSE I CORRELATOR -1--- COMPARATOR CORRECTNESS INDICATORS RECORDERFIG. 6

FRAME ADVANCER LEE E FRANK INVENTOR.

AGENT OPERATOR RESPONSIVE PROGRAMME!) LEARNING APPARATUS FIELD OF THElNVENTlON This invention relates to educational devices and moreparticularly to a programmed learning apparatus wherein in response to aprojected frame, a student interrupts light paths crossing the viewingscreen to sequence the device in accordance with the student responseand the program.

BACKGROUND OF THE INVENTION Many prior art devices which ofierprogrammed learning appear in patents and publications as well as on themarket. Some of these devices are elaborate and expensive multi-stationdevices with a computer control center at a remote location. A studentat a station chooses the program desired which is presented andcontrolled by the central computer. Several of these devices use studentanswer responsive programmed learning storage media.

Other such prior art devices are typically multi-unit devices with arelatively small number of student stations and single teacher consoledevices which are under the control of a classroom teacher or otherperson in the immediate presence of the students. The teacher presentsor causes to be presented an oral or displayed statement or question towhich the students are to respond. After the student responses areregistered, the teachers console display shows which students respondedcorrectly, which responded incorrectly and perhaps which did not respondat all. Some of these devices also keep tabulated data of ratios orpercentages of right versus wrong responses and no responses.Scrutinizing this data, the teacher makes a decision whether to goforward to another topic, to give a similar question, or to give moreinstructions on the topic. Several of the disadvantages of such a systemare readily apparent. All the students are forced to go at the samespeed. Although a student can be having trouble learning a certaintopic, he can get no further instruction on it since only a very fewstudents may have given incorrect answers to the question (s) on thattopic. This same student may have to waste time repeating another topicwith others who did not previously learn it although he himself may knowit well. In short, this system fails to solve many of the classicalclassroom instruction problems.

Yet another type of teaching machine is of the single unit studentresponsive programmed learning variety. This type is the predecessor ofa preferred embodiment of the present invention. Such a device typicallyoffers a viewing screen, programmed storage media; associated logic anda student response registering panel consisting of buttons, knobs orother type of selectors remote from the viewing screen. To operate thedevice, the student must read the projected scene, study the possibleresponses mentally, correlate a displayed multiple choice answer with aremotely located response mechanism, and push, pull or turn the responsemechanism in order to register a response. The device then projectsanother scene in accordance with the response registered by the studentand the program on the storage media.

The present invention overcomes many of the disadvantages of the priorart. It is reliable, simple and easy to use, even for a very young childfor whom mentally correlating answers presented on a display screen witha remote answer registering device may pose a problem.

In accordance with the present invention, the student can respond to apresentation by indicating a response directly on the face of thedisplay screen. There is no need to mentally correlate the response thestudent wants to make as presented on a viewer with a remote set ofbuttons, knobs or dials. Instead, as soon as a response comes to themind of the student, almost as a reflex action the student can indicateit by pointing to a chosen response where it is presented on the viewingscreen. There is no sidetracking of the students mind since the soleattention of the student is on the displayed material to be learned.Particularly for a very young child, there is no response registeringmechanism and procedure to be learned.

Furthermore, no elaborate complex of computer control is needed topractice the present invention although it may be incorporated into suchcomputerized systems. Additionally, the instant invention iscomparatively inexpensive and therefore readily available to the averageschool and student.

Since every student has a personal, complete pro grammed instructionalconsole, every student can progress as fast or as slow over the variousparts of the material as personal background dictates. Every student canlearn each topic at optimum speed since students will not be bored withgoing over material already known or learn little of material toorapidly presented by a classroom instructor or instruction controlledteaching machine.

Additionally, in accordance with the present invention, any number ofknown teaching modes may be practiced. Remedial subroutines may beprogrammed into the instructional material that may be presented only tothose needing it. Branching may also be incorporated into the program.This technique presents a topic of learning material, and amultiple-choice question thereon. Depending on the correctness of thestudent's response, a new topic or a needed variety of remedialsequences or subroutines may be presented. After the student who needsit completes the remedial matter and is satisfactorily retested on thetopic, the student proceeds back into the main instructional sequence.

Straight forward timed or untimed testing can also be administered withthe student answers being registered on a permanent or temporary record.

Correct and incorrect response lights can be used. Temporary orpermanent response records can be made to provide the student andteacher with a report on the student's progress.

Auxiliary reward and punishment features such as response indicatinglights, bells and buzzers may be incorporated to retain the interest ofyoung children.

Time for responding can be controlled and coaching frames can beincorporated into routines which take into consideration both the timefor a student to respond and whether or not the response is correct.

Too, instructional presentations alone can be used wherein the studentresponse serves to advance the next frame or the frames can beautomatically sequenced. The device can also be used forentertainexisting systems with minor changes or modifications thereto.

Audio tracks to aid the visual instructions and questions can beincorporated into the storage medium or in a separate auxiliary systemsynchronized with the visual display. Too, audio comments can beprogrammed as replies to student registered responses.

Throughout the specification, reference will be made to AND gates and ORgates in connection with the disclosed circuitry. it is understood thatthe output of an AND gate is true, or enabled, if and only if all inputsto said AND gates are true, and that the output of the AND gate is falseif any one, or all, of the inputs to said AND gate are false. It is alsoto be understood that the output of an OR gate is true, or enabled, ifany, or all, of the inputs to said OR gate are true, and that the outputof the OR gate is false if, and only if, all of the inputs to said ORgate are false.

SUMMARY OF THE INVENTION A preferred embodiment of the present inventionis used on a rear projection viewer with a programmed media such as amicrofilm strip having encoded frames thereon. The programmed media isnot limited to microfilm, but can be any photographic storage media,videotape, cards, paper, plastic or other storage material which can beoptically or electrically projected or directly read. The encoding andprogramming need not be included on the display frames but should beassociated therewith and can be on, for example, an auxiliary magneticor punched paper tape. The frames can be location address encoded tofacilitate the requirements of branching, subroutine, and routine rerunprogramming which calls for frame skipping and out-offrame sequencepresentations in forward and reverse storage media running directions.For simplicity, effciency and economy,among other reasons, microfilm isused with a preferred embodiment of the invention to be discussed below.

Alternatively, the viewing screen can be a television receiver tube faceif a videotape or other televised programmed storage media is used. If adirectly read storage media is used, an appropriate cabinet having aviewing window of transparent glass, plastic or merely an open orcut-out area can be used. A magnetic tape or other type programmedstorage media can also be used with a cathode ray tube display screenand appropriate circuitry. Other well-known types of viewing screenssuitable for use with the present invention will be apparent to thoseskilled in the art.

Positioned around a portion of the periphery of the viewing screen ofthe preferred embodiment are mirrors that intercept some of the lightfrom, preferably, a projection lamp. However, as is normal in such aviewer, most of the light from the lamp passes through the displayedportion of the encoded frame. The mirrors direct the light as beams ontocorresponding light beam photodetectors also positioned around a portionof the periphery of the encoding screen. ,Thus, the light beams form agrid-like pattern across the face of the screen and impinge ontocorresponding photodetectors. When an encoded frame which calls for astudent response is projected on the screen, the light paths areinterrupted by a finger, pencil or other object to point to a studentselected response on the screen. This causes some light beam or beams tobe blocked so that some corresponding photodetector( s) receive nolight. Associated circuitry is thereby enabled and the indicatedresponse is correlated with the coded information on the frame. As aresult, another frame is selected for display in accordance with theprogram and what student response was made. Too, the correctness of theresponse may be indicated to the student by a light, bell, buzzer,printed or punched record. In this manner, the student can learn at aflexible and personally optimum rate.

One object of the invention is to provide a teaching device which iscontrolled by student response indicated on the viewing screen by thestudent viewer.

Another object of this invention is to provide a teaching or testingdevice in which a response can be registered directly on the face of theviewing screen.

It is another object of this invention to provide a new teaching and/ortesting device sufficiently simple to be operable by a small child.

Another object of this invention is to provide a teaching mechanismusing indicator lights or grading counters that can be remote from theteaching device.

Still another object of the invention is to provide a teaching ortesting device wherein there are no moving parts used in the answerregistration and comparison systems.

Yet another object of the invention is to provide a teaching or testingdevice that is readily adaptable for use with many existing teachingsystems.

A further object of the invention is to provide a teaching or testingdevice that is simple and compact.

Still other objects and advantages of the present invention will bereadily apparent to those skilled in the art from the followingdescription and appended claims.

DESCRIPTION OF THE DRAWINGS Reference is now made to the accompanyingdrawings in which like reference numerals and characters designate likeparts and wherein:

FIG. 1 is a simplified perspective view illustrating the apparatus ofthe present invention with a portion of the housing partially brokenaway;

FIG. 2a is a simplified perspective view of a portion of the screenframe showing one photodetector;

FIG. 2b is a simplified perspective view of a portion of the screenframe wherein a mirror is mounted at approximately 45 to the screen;

FIG. 3 is a planar-view of a typical storage media frame format for usewith a preferred embodiment of the invention showing the relativepositions of image and information encoded areas;

FIG. 4 is a simplified schematic diagram of a logic circuit that can beused in practicing the invention;

FIG. 5 is a simplified schematic diagram of another logiccircuit thatcan be used in practicing the inven-- tion;

FIG. 6 is a block diagram of a teaching machine incorporating thepresent invention; and V FIG. 7 is a planabview of analtemative,storage' media frame format.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. I, apreferred embodiment of the teaching device of the present invention isgenerally referred to by the numeral 10. and is enclosed within ahousing 12 on base 11. Arranged inside of housing is programmed media 13which is preferably microfilm having encoded frames thereon. The frontface 14 of housing 12 contains a rear projection viewing screen 16 thatis preferably fabricated of a translucent material. Arranged around theperiphery of screen 16 is a rectangular frame 18 having a recess 30 inwhich are mounted photodetector retainers 32 containing slideablymounted photodetectors 20-A through 20-F. Also mounted in the recess 30of frame 18 are mirrors 22 as shown in FIG. 2b which are preferablyplaced at approximately 45 to front face 14. In the embodiment shown inFIG. 1, six photodetectors 20-A through 20-F are shown, but it will beunderstood that any reasonable number can be used. The manner in whichphotodetectors 20-A through 20-F and mirrors 22 are mounted in frame 18will be discussed in detail hereinbelow with reference to FIGS. 2a and2b. A preferred format for a frame of programmed storage media 13 isshown in FIG. 3. Programmed storage media 13 is positioned for movementthrough a scanning or reading station by a film gate 17. Arrangedbetween screen 16 and programmed media 13 is projection lens 26 which ismounted to housing 12 in optical alignment with the gate 17 and screen16. Projection lamp 28 is connected to a suitable source of electricalpotential (not shown) and emits light that passes through programmedmedia l3 and projection lens 26 to form an image on screen l6. It willbe appreciated that the optical projection system selected is not partof the invention and alternative systems can be utilized by thoseskilled in the art. For purposes of clarity no further detail is shown.Correct and incorrect answer indicating lights 53, 55, 57 and 59 areshown preferably mounted on the base 11 but can be located in any areaof the device viewable by the student. Removable modular printer 61 canbe incorporated to provide a permanent printed record 63 of thestudent's performance. The printer need not be part of the teachingdevice but can be remotely positioned, such as at a teachers desk.

Referring now to FIG. 2a, a simplified perspective view of a portion ofthe frame 18 in which photodetector retainers 32 are mounted is shown inthe vicinity of photodetector 20-F. Frame 18 preferably has arectangular recess or U-shaped channel 30 therein in which photodetectorretainer 32 is slideably mounted. Photodetector retainer 32 has acylindrical hole 34 therein at the bottom of which photodetector 20-F islocated and is connected by wires (not shown) to associated logiccircuitry. Examplary logic circuitry is discussed hereinbelow withreference to FIGS. 4 and 5. Cylindrical hole 34 acts as a light bafilefor the light incident on photodetector 20-F, to insure that a selectedlight beam 29 from projection lamp 28 reflected from mirror 22 reachesphotodetector 20-F, and that no appreciable ambient room light falls onphotodetector 20-F. Photodetector retainer 32 can be made of blackLucite, metal, or other opaque material. The mounting of the remainingphotodetectors is similar to that of photodetector 20-F which is used asan example.

Turning now to FIG. 2b, the part of frame 18 devoted to holding mirrors22 in rectangular recess 30 is shown. Frame 18 is preferably made ofLucite, glass or other transparent material. The portion of frame 18holding the mirror can also be L-shaped and opaque although atransparent U-shaped recess 30 is shown. Too, the frame 18 need not betransparent if portions between the mirror and the light incidentthereon from source 28 are cut out. However. the use of a transparentframe enables easy changing of mirror positions, adding mirrors oreliminating them. Alternatively the mirrors need not be individuallypositionable and two sides of the screen can have continuous stripmirrors mounted there with photocells located on the other respectiveopposite two sides. Beam selection would then be by the retainers 32with holes 34 containing the photocells. Other types of photodetectorsand mirror mountings which can be substituted for those shown will beapparent to those skilled in the art.

Prisms or other reflecting bodies can be substituted for the mirrors. Aseparate light source can be used to establish the beams or individualbeam sources. Fiber optics can be used to provide beam sources. Anadvantage of the preferred embodiment is that mirrors are inexpensiveand efficient use is made of the frame illuminating source, adding tothe simplicity and effciency of the apparatus embodying the invention.

Referring now to FIG. 3, a possible format for a frame of programmedmedia 13 is shown in which such media is a film 13 having an image area36, encoded areas 38 and 39 and perforations 40. Encoded areas 38 and 39correspond to photodetector positions on two sides of rectangular frame18 seen in FIG. 1.

Operation of the device is best understood with reference to FIGS. 1, 3,4 and 6. Light rays A-F originate from projection lamp 28 and passthrough programmed media 13 and projection lens 26 to reflect from thesurface of mirrors 22 and impinge upon photodetectors 20-A through 20-Frespectively. When an object such as a finger is placed in a position tointerrupt the light paths to, preferably, at least two of thephotodetectors, an electric circuit connected to the.

photodetector is activated, as will be discussed hereinbelow withreference to FIG. 4. By use of the proper code in coded areas 38 and 39of programmed media 13 seen in FIG. 3, one or more photodetectors can beblocked, reducing the number of intersecting beams under considerationfor that particular frame of programmed media 13.

Referring now to FIG. 4, a circuit is shown that can be used with theteaching device shown in FIG. 1. Leads 4l-A through 4l-F ofphotodetectors 20-A through 20-F, respectively, are connected throughresistors 44-A through 44-F, respectively, to the positive terminal of aDC voltage supply 42. Lead 43-A of, photodetector 20-A is connected toan input tenninal of AND gate 45, and to input terminal 66 of AND gate49. Lead 43-3 of photodetector 20-8 is connected to input terminal 63 ofAND gate 47 as well as to input terminal 69 of AND gate 51. Lead 43-E ofphotodetector 20-E is connected to input terminal 65 of AND gate 47 andto input terminal 62 of AND gate 45. Lead 43-F of photodetector 20-F isconnected to input terminal 71 of AND gate SI and also to input terminal68 of AND gate 49.

The output leads from AND gates 45, 47, 49 and 51 are connected to thenegative terminal of DC voltage supply 42 through individuallyassociated lamps 53, 55 S7 and 59 respectively.

Assume that the placing of a finger at the intersection of light beams Aand C (see FIG. 1) represents the correct response to the question posedby the projected image on screen 16. The encoded area 38 on programmedmedia 13 causes no light to reach photodetectors -1-3 and 20-F.Therefore, photodetectors 20-A, 20-C, 20-E, and 20-F receive no light.The resistances of photodetectors 20-A, 20-C, 20-E and 20-F aretherefore higher than the resistance of photodetectors 20-8 and 20-D.The voltage drops across resistors 44-8 and 44-D are therefore greaterthan the voltage drops across resistors 44-A, 44-C, 44-E and 44-F. Thevoltage of input terminals 60, 61, and 62 of AND gate 45, inputterminals 64 and 65 of AND gate 47, input terminals 66 and 68 of ANDgate 49, and input terminal 71 of AND gate 51 is higher than thevoltages at input terminal 63 of AND gate 47, input terminal 67 of ANDgate 49, and input terminals 69 and 70 of AND gate 51. AND gate 45 isenabled, causing lamp 53 to light. AND gates 47, 49 and 51 are notenabled. Therefore, lamps 55, 57 and 59 remain unlit. The lighting oflamp 53 signifies that the proper answer has been given. As directed bythe encoded Their resistances are now higher than the resistances ofphotodetectors 20-A and 20-D. The voltage drops across resistors 44-Aand 44-D are therefore greater than the voltage drops across resistors44-13, 44-C, 44-E and 44-F. The voltages at input terminals 61 and 62 ofAND gate 45, input terminals 63, 64 and 65 of AND gate 41, inputterminal, 68 O AN gate 49, and input terminals 69 and 71 of ANDgate 51are higher than the voltages at input terminal 60 of AND gate 45;

. input terminals 66 and 67 of AND gate 49, and input terminal 70 of ANDgate 51. AND gate 47-is therefore enabled, causing lamp 55 to light. ANDgates 45, 49 and 51 are not enabled, so lamps 53,57 and 59 remain unlit,The lighting of lamp 55 signifies that a wrong answer has been givenand, in accordance with the code on the displayed frame and the responseoperator registered, another frame is displayed. 1

Referring now to FIG. 5, circuitry is shown that can be used with ateaching device incorporating the present invention utilizing 12photodetectors 80-A through 80-L and yielding 32 possible lightintersections. The negative lead of every photodetector 80-A through80-L is connected to the negative terminal of DC voltage supply 82. Thepositive leads photodetectors 80-A through 80-L are connected throughrespective resistors 81-A through 81-L to the positive terminal of DCvoltage supply 82.

Positive leads from photodetectors 80-A are connected to input terminals85, 97 and 99 of OR gates 120, 122 and 123 respectively. The positiveterminal of photodetector 80-8 is connected to input terminals 86 and 98of OR gates 120 and 122, respectively. Positive leads from photodetector80-C are connected to input terminals 87 and 100 of OR gates 120 and123, respectively. The positive terminal of photodetector 80-D isconnected to input terminal 88 of OR gate 120. The positive terminal ofphotodetector 80-E is connected to input terminals 89, '101, 105 and 109of OR gates 121, 124, 125 and 126, respectively. A positive lead fromphotodetector 80-F is connected to input terminal 90 of OR gate 125. Thepositive terminal of photodetector 80-G is connected to input terminals91, 103 and 110 of OR gates 121, 124 and 126, respectively. The positiveterminal of photodetector 80-I-l is connected to input terminal 92 of ORgate 121 and to input terminal 104 of OR gate 124. The positive terminalof photodetector 80-1 is connected to input terminals 93, 107 and 111 ofOR gates 121, 125 and 126, respectively. The positive terminal ofphotodetector 80-.[ is connected to input terminal 94 of OR gate 121 andto input terminal 108 of OR gate 125. Positive leads from photodetector80-K are connected to input terminal 95 of OR gate 121 and to inputterminal 112 of OR gate 126. The positive terminal of photodetector 80-Lis connected to input terminal 96 of OR gate 121. OR gates 120 and 121input to AND gate 130 by lines 127 and 128, respectively.

The purpose of OR gate 120 is to detect if any vertical beam of lighthas been blocked, that is, if any one of photodetectors -A, 80-B, 80-Cor 80-D has been darkened. Placing a finger on screen 16 so thatno-light reaches photodetector 80-A makes the resistance ofphotodetector 80-A higher than the resistance of any of thephotodetectors 80-8, 80-C or 80-D. The voltage drop across resistor 81-Ais less than the voltage 1 drop across any of the resistors 81-B, 81-Cor 81-D. Input terminal experiences a higher voltage than inputterminals 86, 87, or 88 of OR gate 120. The output of OR gate over line127 is hence energized signifying that one of the vertical light beamshas been interrupted. Analogous analyses can be made for when any of thephotodetectors 80-B, 80-C or 80-D receive 81-1, 81-1, 81-K or 81-L, andhence the voltage appearing at input terminal 89 of OR gate 121 ishigher than the voltage appearing at input terminals 90, 91, 92, 93, 94,95 or 96 thereof. Line 128 is energized from OR gate 121 to signify thatone horizontal light beam any one of the photodetectors 80-F, 80-G,80-H, 80-l, 80-1, 80-K or 80-L receiving no light.

To detect whether one intersection of horizontal and vertical lightbeams has been blocked, AND gate 130 is has been interrupted. Similaranalyses can be made for provided. Assuming line 127 is energized,signifying that any one of photoconductors 80-A through 80-D has beendarkened, and also that line 128 is energized, signifying that any oneof photoconductors 80-E through 80-L has been darkened, the output line131 of AND gate 130 will be energized. Output 131 can be to an electriclight such as 53, 55, 57 or 59as shown in FIG. 1 to indicate that ananswer has been given.

OR gate 122 is used to detect whether any beam of light on the left halfof the screen has been blocked by determining whether either ofphotodetectors 80-A'or 80-B has been darkened. lf a finger is placed onscreen 16 so that no light reaches photodetector 80-A, its resistancewill be higher than the resistance of photodetector 80-B. The voltagedrop across resistor 8l-A will be then less than the voltage drop acrossresistor 81-8, and hence the voltage at input terminal 97 will be higherthan the voltage at input terminal 98 of OR gate 122. Therefore, OR gate[22 outputs over line 132, to

signify that the light beam directed at photodetector 80-A has beeninterrupted. A similar explanation can be made for when photodetector80-B, which is also in the left half of screen 16 receives no light.

To detect if any beam of light in the left half of either the right orleft half of the screen has been blocked, that is, if either ofphotodetectors 80-A or 80-C has been darkened, OR gate 123 is provided.A finger placed on screen 16 so that no light reaches photodetector 80-Araises the resistance of photodetector 80-A so that it is higher thanthe resistance of photodetector 80-C. The voltage drop across resistor8l-A is less than the voltage drop across resistor til-C, and hence thevoltage at input terminal 99 of OR gate 123 is higher than thevoltageappearing at input tenninal 100. An output from OR gate 123 overline 134 occurs, signifying that the light beam directed atphotodetector 80-A has been interrupted. An analogous situation existsif photodetector 80-C, which is also in the left half of one of thehalves of screen 16, is receiving no light.

OR gate 124 will determine whether any beam of light in the top half ofscreen 16 has been blocked, that is, if any one of photodetectors 80-E,80-F, 80-6, or 80-H has been darkened. If a finger has been placed onscreen l6 so that no light reaches photodetector 80-E, the resistance ofphotodetector 80-E is higher than the resistance of any ofphotodetectors 80-E, 80-6, or 80-l-l. The voltage drop across resistor8l-E is therefore less than the voltage drop across any of the rethevoltage drop across any of the resistors 8l-F, 81-1 or 81-], and henceless than the voltage appearing at input terminal 106, 107. or 108 of ORgate 125. The output of OR gate 125 over line 1-38 will signify that oneof the light beams in the top half of either the top or bottom half ofscreen 16 has been interrupted. A similar situation exists when one ofthe photodetectors 80-F, 80-l, or 80-J is receiving no light.

To determine if any beam of light in the top half of anyq'uarter of thescreen 16, divided horizontally, has been blocked, that is, if any oneof photodetectors 80-E, 80-6, 80-1, or 80-K has been darkened, OR gate126 is used. By placing a finger on screen so that no light reachesphotodetector 80-E, the resistance of photodetector 80-E is raised to behigher than the resistance of any of the photodetectors 80-6, 80-1, or80-K. The voltage drop across resistor 8l-E is now less than the voltagedrop across any of the resistors 81-6, 81-], or Bl-K. The voltage atinput terminal 109 is now higher than the voltage appearing at inputterminals 110, 111, or 112, energizing OR gate 126 to output over line140. This signifies that one of the light beams in the top half of anyquarter of screen 16, divided sistors BI-F, 81-6, or 81-41, and thevoltage at input terminal 101 .is higher than the voltage at inputterminals 102, 103 or 104 of OR gate 124. The output of OR gate 124 overline 136 signifies that one of the light beams in the top half of screen16 has been interrupted.

Analogous analyses can be made for any one of the photoconductors 80-F,80-6, or 80-H receiving no tors -E, 80-F, 80-l, or 80-J has beendarkened. Assuming a finger has been placed on screen 16 so that nolight reaches photodetector 80-E, the resistance of photoconductor 80-Ewill be higher than the resistance of any of the photodetectors 80-F,80-1, or 80-J. The

voltage drop across resistor 8l-E is therefore less thanlogicrepresented by horizontally, has been interrupted. The explanationpresented hereinabove is based upon the assumption that photodetector80-E is receiving no light, and a similar description can be made forany one of the photodetectors 80-6, 80-1, or 80-K receiving no light.

The circuit shown in Fl6,. 5 is capable of indicating 32 intersections.It will be appreciated by one skilled in theart that the addition ofeachadditional OR gate doubles the number of defined positions. Thenumber of photodetectors required is equal to two times the square rootof the desired number of intersections, for example, 32 photodetectorsare needed to indicate 256 intersections.

Referring now to FIG. 6, a block diagram of a teaching machineincorporating the present invention is shown. Photodetectors such as20A-20F or 80A-80L are represented by block 150. Controlling inputs tothe photodetectors is photodetector enabling lock 152 which can be thatshown in FIGS. 4 or 5. esponse. correlating comparator 154 can also bethat shown in FIGS. 4 and 5 or may be a program controlled logic as iswell known by those skilled in the art. Comparator 154 compares theoutput of photodetectors and frame code reader 156 for reading codedframe 158 which can be of the format shown in FIG. 3. The coding on theframe displayed controls through enabling circuit 152 whichphotodetectors in block 150 are operatively connected to comparator 154.Comparator 154 can output to student responsecorrectness indicators suchas lights 53, 55, 57 and 59, a response recorder 161 such as the printer61 and a frame advancement mechanism 162.

With reference to FIG. 7, a storage medium 13 having perforations 40 andcode format 150 which has several distinct answer columns or areas 152rather than intersections can be used. A set of parallel light beamsextending across the display screen between two opposite sides or, as isshown, from top to the bottom of frame 18 is provided. An interruptionof one of the beams can be registered by a finger or other object. Ifone photodetector is enabled, when the light to it is cut off, a correctresponse is registered.

it is possible to make the system work with more than one correct answerto a question displayed on the screen. The electronics to do this can beprovided as those to a preferred embodiment were to accommodate any suchrequirements.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention.

I claim:

1. An operator responsive device having a projection lamp and screen fordisplaying information from a response encoded programmed storage mediumbearing encoding corresponding to the displayed information, said devicecomprising:

means for directing light from said lamp into light beams adjacent toand transversing said display screen;

photodetectors positioned to receive light from said light beamsprovided such light beams remain uninterrupted by an operator response;

circuit means operatively connected to the photodetectors and responsiveto the encoded medium for comparing an operator response to the encodingwhich corresponds to the information displayed; and

means operatively connected to said circuit means for producing signalsrepresentative of the result of comparisons made by said circuit means.

2. The device of claim 1 wherein said light beam forming and directingmeans comprises means for reflecting light beams adjacent to andtransversing said display screen.

3. A teaching machine having a projection lamp and screen for displayinginformation from a response encoded programmed media containingquestions and encoded answers stored thereon, said machine comprismg:

photodetectors positioned to receive light directed across the front ofsaid display screen;

means for illuminating said photodetectors with light from said lamp, astudent response being indicated.

by the interruption of light impinging on at least one of saidphotodetectors; 7

means for indicating the correctness of a student response; and

means operatively connected to said photodetectors for comparing theencoded answer for the displayed question with the student response andfor activating said indicating means.

4. The teaching machine of claim 3 wherein said light comprises a gridof light beams across and closely spaced from the front face of saiddisplay screen.

5. A display device having a projection lamp, a media moving mechanismand a screen for displaying information from a response encodedprogrammed media, said device comprising:

means for directing light from said projection lamp across the face ofsaid screen;

photodetectors positioned to receive said light having outputs inaccordance with the amount of light impinging thereon; and

0 projection lamp and screen for displaying information from a responseencoded programmed storage media and a media moving mechanism, saidmachine comprising:

photodetectors having outputs corresponding to light impinging thereon;

means for illuminating the photodetectors with light from said lamp bydirecting light beams to form a grid-like pattern across the face of thescreen, whereby a student response is registered by interruption of atleast one of said light beams;

first circuit means for controlling said media moving mechanism;

second circuit means for comparing the encoding corresponding to thedisplayed information with the outputs of said photodetectors; and

third circuit means for indicating the correctness of a studentresponse, such that when a student response is registered, said secondcircuit means enables both said first circuit means to move the media inaccordance with the comparison results and said third circuit means toindicate the correctness of the student response.

7. The machine of claim 6 wherein said third circuit means comprisesmeans for indicating a correct response and means for indicating anincorrect response.

8. The machine of claim 6 wherein said third circuit means comprisesmeans for recording the correctness of a student response.

9. An operator responsive device having a media moving mechanism, aprojection lamp and a screen for displaying information from a responseencoded programmed media, said device comprising:

photodetectors positioned to receive light beams from the lamp directedtransversely across and adjacent said screen;

means for illuminating said photodetectors with light from said lamp;first circuit means associated with said photodetectors for providing anoutput responsive thereto;

second circuit means responsive to the encoding on the mediacorresponding to the displayed inform ation for providing an outputresponsive thereto; and

comparison means for comparing the outputs of said first and secondcircuit means and for actuating the media moving mechanism in accordancewith the result. of the comparison, such that when information isdisplayed and a response is registered by an operator initiatedinterruption of at least one of said light beams, said media movingmechanism is actuated and said media is moved in accordance with theprogram and the operator response.

10. The device of claim 9 further comprising means to said comparisonmeans.

l3 14 11. The device of claim 9 further comprising means directing lightbeams from the lamp across the face for indicating an incorrect responseoperatively conofthe screen to selectively located photodetectors;

nected to said comparison means.

12. The device of claim 9 further comprising means for recording theresponse.

l The method (if usmg a :eacnng mach ne havirt g a light beaminterruption; and pro-lee amp an screen or aymg m moving the media inresponse to comparison of enfrom response encoded programmed media, saidcoding corresponding to the displayed information method comprising. d h0d t t t t displaying response encoded information on the 10 an F 0t eso or Pu screen;

interrupting at least one light beam to enable the circuitry to advancethe media in accordance with encoding and photodetector output afiectedby

1. An operator responsive device having a projection lamp and screen fordisplaying information from a response encoded programmed storage mediumbearing encoding corresponding to the displayed information, said devicecomprising: means for directing light from said lamp into light beamsadjacent to and transversing said display screen; photodetectorspositioned to receive light from said light beams provided such lightbeams remain uninterrupted by an operator response; circuit meansoperatively connected to the photodetectors and responsive to theencoded medium for comparing an operator response to the encoding whichcorresponds to the information displayed; and means operativelyconnected to said circuit means for producing signals representative ofthe result of comparisons made by said circuit means.
 2. The device ofclaim 1 wherein said light beam forming and directing means comprisesmeans for reflecting light beams adjacent to and transversing saiddisplay screen.
 3. A teaching machine having a projection lamp andscreen for displaying information from a response encoded programmedmedia containing questions and encoded answers stored thereon, saidmachine comprising: photodetectors positioned to receive light directedacross the front of said display screen; means for illuminating saidphotodetectors with light from said lamp, a student response beingindicated by the interruption of light impinging on at least one of saidphotodetectors; means for indicating the correctness of a studentresponse; and means operatively connected to said photodetectors forcomparing the encoded answer for the displayed question with the studentresponse and for activating said indicating means.
 4. The teachingmachine of claim 3 wherein said light comprises a grid of light beamsacross and closely spaced from the front face of said display screen. 5.A display device having a projection lamp, a media moving mechanism anda screen for displaying information from a response encoded programmedmedia, said device comprising: means for directing light from saidprojection lamp across the face of said screen; photodetectorspositioned to receive said light having outputs in accordance with theamount of light impinging thereon; and circuit means for comparing theoutputs of the photodetectors with the encoding on said mediacorresponding to the information displayed, whereby upon interruption ofthe light falling upon at least one of the photodetectors, said circuitmeans actuates said mechanism to move said media in accordance with theresult of the comparison.
 6. A student responsive teaching machinehaving a projection lamp and screen for displaying information from aresponse encoded programmed storage media and a media moving mechanism,said machine comprising: photodetectors having outputs corresponding tolight impinging thereon; means for illuminating the photodetectors withlight from said lamp by directing light beams to form a grid-likepattern across the face of the screen, whereby a student response isregistered by interruption of at least one of said light beams; firstcircuit means for controlling said media moving mechanism; secondcircuit means for comparing the encoding corresponding to the displayedinformation with the outputs of said photodetectors; and third circuitmeans for indicating the correctness of a student response, such thatwhen a student response is registered, said second circuit means enablesboth said first circuit means to move the media in accordance with thecomparison results and said third circuit means to indicate thecorrectness of the student response.
 7. The machine of claim 6 whereinsaid third circuit means comprises means for indicating a correctresponse and means for indicating an incorrect response.
 8. The machineof claim 6 wherein said third circuIt means comprises means forrecording the correctness of a student response.
 9. An operatorresponsive device having a media moving mechanism, a projection lamp anda screen for displaying information from a response encoded programmedmedia, said device comprising: photodetectors positioned to receivelight beams from the lamp directed transversely across and adjacent saidscreen; means for illuminating said photodetectors with light from saidlamp; first circuit means associated with said photodetectors forproviding an output responsive thereto; second circuit means responsiveto the encoding on the media corresponding to the displayed informationfor providing an output responsive thereto; and comparison means forcomparing the outputs of said first and second circuit means and foractuating the media moving mechanism in accordance with the result ofthe comparison, such that when information is displayed and a responseis registered by an operator initiated interruption of at least one ofsaid light beams, said media moving mechanism is actuated and said mediais moved in accordance with the program and the operator response. 10.The device of claim 9 further comprising means for indicating a correctresponse operatively connected to said comparison means.
 11. The deviceof claim 9 further comprising means for indicating an incorrect responseoperatively connected to said comparison means.
 12. The device of claim9 further comprising means for recording the response.
 13. The method ofusing a teaching machine having a projection lamp and screen fordisplaying information from response encoded programmed media, saidmethod comprising: displaying response encoded information on thescreen; directing light beams from the lamp across the face of thescreen to selectively located photodetectors; interrupting at least onelight beam to enable the circuitry to advance the media in accordancewith encoding and photodetector output affected by light beaminterruption; and moving the media in response to comparison of encodingcorresponding to the displayed information and photodetector output.